The development of vaccine to protect against infection and disease due to human immunodeficiency virus (HIV) is an important public health goal worldwide. Sub-Saharan Africa is a part of the world that is among the most effected by the current AIDS pandemic and is an important geographic area for consideration in the design of international trials of AIDS/HIV vaccines. This proposal is a response to RFA number AI-92-05 to establish collaborative studies in Zimbabwe to develop baseline data and the infrastructure needed to conduct AIDS/HIV vaccine trials. The goals of the two year program are 1) to determine the incidence of HIV infection in factory workers already known to be at risk for HIV infection, 2) to identify the biologic and behavioral co-factors of heterosexual transmission of HIV, 3) to obtain samples for genetic and serologic characterization of viruses currently causing infection, and 4) to build the infrastructure needed for natural history, treatment and vaccine trials among collaborators at Stanford University, the University of Zimbabwe, the Blood transfusion Service, and the National AIDS Control Programme of Zimbabwe. The proposal will create core facilities to build on existing epidemiologic data by initiating new investigations and supporting ongoing serologic testing of well defined cohorts of factory workers (n = 2,000) and the spouses of seropositive workers (n = 200) in Harare, Zimbabwe. This study is in a setting in which there are well characterized risk factors for HIV infection and established mechanisms for tracking individuals over years. The investigators have worked together over the past 6 years to produce epidemiologic and virologic data that has impacted on public health policy in Zimbabwe. The proposed studies will focus on the incidence of new infection, the relationship of STD to acquisition and transmission of HIV, and the genetic and serologic characteristics of HIV in Zimbabwe. The program will draw on expertise in the country in Medicine, Medical Microbiology, Epidemiology, and Public Health from the University of Zimbabwe, the Ministry of Health, and the National Blood Transfusion Service. The investigators propose to create a local advisory board to provide guidance in the design and execution of these studies, and ultimately of clinical trials.